Wafer Manufacturing Cleaning Apparatus, Process And Method Of Use

ABSTRACT

A cleaning wafer or substrate for use in cleaning, or in combination with, components of, for example, integrated chip manufacturing apparatus. The cleaning substrate can include a substrate having varying predetermined surface features, such as one or more predetermined adhesive, non-tacky, electrostatic, projection, depression, or other physical sections. The predetermined features can provide for more effective cleaning of the components with which they are used, such as an integrated chip manufacturing apparatus in the place of the integrated chip wafer. The cleaning substrate can be urged into cleaning or other position by vacuum, mechanical, electrostatic, or other forces. The cleaning substrate can adapted to accomplish a variety of functions, including abrading or polishing. The cleaning substrate may be made by a novel method of making, and it may then be used in a novel method of use I combination with chip manufacturing apparatus.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application entitled“Wafer Manufacturing Cleaning Apparatus, Process, And Method Of Use,”Ser. No. 16/136,965, filed Sep. 18, 2018, which claims priority throughApplicant's prior U.S. patent application entitled “Wafer ManufacturingCleaning Apparatus, Process, And Method Of Use,” Ser. No. 15/419,840,filed Jan. 30, 2017, and granted Oct. 23, 2018, as U.S. Pat. No.10,109,504, which claims priority through Applicant's prior U.S. patentapplication entitled “Wafer Manufacturing Cleaning Apparatus, Process,And Method Of Use,” Ser. No. 13/971,619, filed Aug. 20, 2013, andgranted Mar. 14, 2017, as U.S. Pat. No. 9,595,456, which claims prioritythrough Applicants' prior U.S. patent application entitled “WaferManufacturing Cleaning Apparatus, Process, And Method Of Use,” Ser. No.13/725,827, filed Dec. 21, 2012, and granted Jun. 19, 2018, as U.S. Pat.No. 10,002,776, which claims priority through Applicants' prior U.S.patent application entitled “Wafer Manufacturing Cleaning Apparatus,Process, And Method Of Use,” Ser. No. 12/760,543, filed Apr. 14, 2010,which claims priority through the Applicants' prior U.S. Provisionalpatent application entitled “Wafer Manufacturing Cleaning Apparatus,Process, And Method Of Use,” Ser. No. 61/169,007, filed Apr. 14, 2009,all of which prior applications are hereby incorporated by reference intheir entirety. It is to be understood, however, that in the event ofany inconsistency between this specification and any informationincorporated by reference in this specification, this specificationshall govern.

TECHNICAL FIELD

The present disclosure relates generally to the field of cleaningmaterials for integrated circuit manufacturing equipment.

BACKGROUND

Integrated circuit chips are complex, typically highly miniaturizedelectronic circuits that can be designed to perform a wide variety offunctions in electronics of nearly every kind. See an integrated circuitchip shown in FIG. 1 for example. Differing integrated chips includediffering electrical components such as transistors, resistors,capacitors and diodes connected to each other in different ways. Thesecomponents have differing behaviors, and assembling these differingcomponents in myriad differing ways on chips yields similarly differingelectronic functions performed by the differing chips.

As a result, integrated chips have become ubiquitous in electronics ofnearly every type in the modern industrialized world. Consequently, thesize of the worldwide integrated chip market has long been enormous.

Integrated chips are, however, difficult to manufacture, requiring superclean manufacturing environments and equipment. As these chips aremanufactured, they too must be maintained in a super clean condition.The chip manufacturing process, however, necessarily leads tocontamination of the chip manufacturing apparatus, which leads tocontamination of the manufactured chips. This contamination can andoften does damage or even ruin the resulting chips. Consequently, thechip manufacturing industry has long been engaged in seeking moreeffective, more efficient, and less costly techniques for maintaining asuper clean environment during manufacturing of integrated circuitchips. See, e.g., U.S. Pat. No. 6,777,966 to Humphrey et al., which ishereby incorporated by reference.

In this regard, chips are commonly manufactured on “stages” in the chipmanufacturing apparatus. Differing stages are used to form differingportions of electronic circuitry components on the wafer. See, e.g.,U.S. Pat. No. 6,256,555 to Bacchi et al, U.S. Pat. No. 6,155,768 toBacchi et al. A stage can often have a complex surface structure,including burls, flat areas, vacuum ports, and other structures. Id

During wafer manufacturing, small particulate contaminate debris buildsup on the equipment and the stages. For example, the build-up ofparticulate contaminants on stages can affect the focus and accuracy ofthe photolithography process during chip circuit production. Removingcontaminants from the crevices, valleys, and other surface structure onthe surface of the various stages and wafer handling equipment has longpresented a substantial challenge.

Offline cleaning of stages and handling equipment commonly requires tooldowntime and opening of the automated wafer handling equipment. Theintegrated circuit manufacturer incurs a significant cost as equipmentdowntime for this cleaning operation lowers production throughput.

In-line cleaning techniques have sought to avoid the need to shut downthe wafer processing tool and to increase production efficiency andyield of integrated circuit wafers. One in-line cleaning technique hasinvolved using a non-tacky polyimide surface on a cleaning wafer tocollect debris via static charge on the wafer manufacturing stages andmanufacturing apparatus. See, e.g., processes of such companies as NittoDenko, Metron Technology, and Applied Materials. Other in-line cleaningtechniques have utilized generally planar wafers or wafers with slightsurface roughness produced with viscoelastic, polymers such as silicone(e.g., see additional processes of Nitto Denko, Metron Technologies, andApplied Materials).

Typically, the cleaning wafer substrates of the prior art have not hadsufficient surface adhesion, or “tackiness,” to achieve the desiredlevel of debris collection. The reason for this short-coming is that ifthe level of surface adhesion is sufficient to remove the majority ofthe foreign particulates in a prior art planar wafer, the adhesionbetween the cleaning surface and the contact surfaces of the hardwareoften has prevented adequate release and removal of the cleaning waferfrom manufacturing hardware, wafer stages, or chucks.

Consequently, the prior art cleaning wafers have typically been designedwith limited or no tack, the result being that the use of a cleaningwafer in a planar wafer substrate without adhesive properties orinsufficient adhesive properties typically has not sufficiently andeffectively removed foreign matter or particulates. The prior art wafershave also commonly had planar surfaces, relying upon deformation ofthese surfaces when in contact with surfaces to be cleaned by them. Thedeformation is often accomplished by applying a vacuum, forcing thecompressible cleaning wafer to deform against a mating surface of thesurface to be cleaned by the cleaning wafer.

Also available are off-line cleaning methods such as use of a grindstoneabrasion (ASML) combined with vacuum based particle collection to removedebris remaining after using the previously described cleaning wafertechniques. This type of cleaning process is an add-on feature atconsiderable cost. The grindstone cleaning also typically requires tooldowntime and opening of the automated wafer handling equipment.

SUMMARY

The applicants have invented a cleaning wafer or substrate, relatedapparatus, and methods of manufacture and use for, among other things,removal of foreign matter and particulates from surfaces of automatedand manual integrated chip manufacturing hardware, such as stages orwafer chucks and associated structures. In some embodiments, the shapeand physical attributes of the cleaning wafer are preformed to providevarying surface features that matingly engage, surround, or abut thevarying contours of the surface to be cleaned on an stage, chuck, orother aspect of chip handling or manufacturing equipment to be cleanedby the cleaning wafer.

In some embodiments, the cleaning wafer is especially suited to cleannon-planar surfaces and interact non-destructively with those surfacesand their environment.

In certain embodiments, the structural surface and other features of acleaning wafer, the size, shape, orientation, and location of thestructural features may be varied significantly to accommodate differentprocess tools, stages, chucks, or other components to be cleaned by thecleaning wafer.

In certain embodiments, these structural surface features may be formedin an elastic polymer substrate underneath the cleaning layer or addedas separate features bonded to or laminated onto the cleaning substrate.The structural feature may consist of one or more cleaning polymers andunderlying primary substrates, other elastic polymers having varyingtack levels, other polymers of variable compressibility, or otherpolymers that exhibit little or no tack properties.

In certain embodiments, the cleaning wafer is made of polymer or similarresilient material and the cleaning surface of the cleaning wafer issufficiently compliant to deform around the burls and micro-burls andcollect debris that may have accumulated around the periphery of the pincontact surface on a chip manufacturing stage.

In some embodiments, foreign matter may be removed from the waferhandling hardware and stages by using the adhesive or tacky property ofthe cleaning section of the cleaning wafer.

Certain embodiments include one or more compressible offsets or otherspecifically located surface features or projections on or formed withina cleaning wafer. In some embodiments, these features can reduce orprevent surface contact with the wafer handling hardware, stage, orchuck until vacuum, electrostatic, or other force collapses the targetoffset or other surface feature or projection.

In some embodiments, upon compression of the wafer's projectingcompressible offset surface features, greater, and in some cases, fullsurface contact of the cleaning media can be made with the surface to becleaned.

In certain embodiments, upon release of the vacuum, electrostatic orother force, the wafer's projecting compressible offset or varyingfeatures can have sufficient resilience to rebound and release theadhesive cleaning surface from the chip manufacturing hardware, stage,or chuck, thereby removing the foreign particles from the cleanedsurface.

In some embodiments, various types of compliant and geometrical featureson the cleaning substrate prevent catastrophic adherence at differentsteps within the wafer handling and placement sequence.

In certain embodiments, the compliance characteristics of the cleaningwafer substrate may be altered by including multiple layers or sectionswith different compliance properties to improve the conformabilityaround the geometric features of the chip manufacturing hardware, suchas stage, in order to achieve maximum foreign particle contact andremoval.

In some embodiments that include a pin or burl chuck on the stage, forexample, the cleaning wafer's projecting compressible offset featurescan be pre-positioned at locations outside the pin area or in specificlocations within the pitch of the pins and burls so a differing wafersection, such as, for example, a flat, tacky cleaning surface, maycontact the pin tips or other desired section of the chuck, to removedebris.

In some embodiments, the featured structures of the cleaning wafer maybe formed from a non-tacky resin to provide offset to the surface sothat the cleaning polymer may be positioned in the recessed area betweenthe offset or varying structures in or on the cleaning wafer.

In certain embodiments, the predetermined substrate features orprotrusions may consist of cleaning materials and the bare wafer ornon-tacky resin may reside between the protrusions to provide cleaninginto corresponding adjacent recessed areas of a stage or other structureto be cleaned.

In some embodiments, some wafer handling hardware, stages, and chucksmay have limited and discrete components that may be damaged by contactwith cleaning media. In such cases, the cleaning wafer may havediffering sections with varying degrees of surface tack to allowcleaning of, for example, ejector pins or specific burl areas with highsurface tack while sensitive or problem areas, such as that for cleaningan outer sealing ring, may have relatively less or no tack, in order,for example, to allow vacuum sealing to, and release from, the ring uponremoval of the vacuum.

In some embodiments, the features may be molded directly into thecleaning material eliminating the need for additional materials in thestructure. In certain embodiments, instead of forming the surfacefeatures from a single polymeric material, various features may becreated and located across the cleaning surface by adhering separategeometric features made from the same or differing elastomeric polymeror resin materials. For example, geometric offset features such ashemispheres, pyramids, or other geometries may be formed separately froma hard resin and then adhesively bonded to the cleaning polymer surface.

In some embodiments that include a cleaning wafer handling chuck withone or more vacuum ports, grooves, or nipples, the locations of thecompressible offset features are predetermined and located on thecleaning wafer to facilitate debris collection from within the areacircumscribed by the vacuum features.

In at least one embodiment, one or more components of a chipmanufacturing and handling system (such as transport equipment, rotationand alignment equipment, stages, or chucks) can be cleaned by the use ofa cleaning wafer having a shape predetermined to facilitate transport ofthe cleaning wafer through the wafer processing equipment.

In some embodiments, abrasive filler particles of aluminum-oxide,silicon-carbide, diamond, or other materials may be utilized inconjunction with a cleaning wafer to provide a scrubbing action, inorder to dislodge tenacious particulates from the flat surface or theburls and microburls of the wafer chuck.

In some embodiments, the electrostatic charge of the cleaning wafersurface may be altered to improve the attraction to foreign particulatematter.

In some embodiments, conductive filler may be added to the compositionof the cleaning surface polymer on or in the cleaning wafer. In someembodiments, doing so can improve the cleaning wafer's electrostatichold-down force when used to clean wafer chucks.

In some embodiments, the cleaning wafer or substrate may then beimplemented in standard automated wafer handling equipment under normalprocessing conditions. Specially adapted equipment may also be utilized,but in some embodiments, one aspect of the cleaning process can allowuse of the cleaning in line during the wafer manufacturing process andwithout need for customized equipment.

It is understood that the foregoing Background and Summary recites somebut not all aspects of the background art and some, but not all aspects,features, and advantages of differing embodiments of this specification.It is therefore also to be understood that all embodiments will notnecessarily address issues noted in the Background. Additional aspects,features, and advantages of the embodiments of this specification willbecome apparent as this specification proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS

The applicants' preferred and other embodiments are set forth inassociation with the accompanying drawings in which:

FIG. 1 is a perspective view of a prior art integrated circuit chip;

FIG. 2 is a perspective schematic view of the underside, cleaning sideof one embodiment of a cleaning wafer with multiple protruding points orpeaks extending from the surface of the cleaning wafer;

FIG. 3 is a perspective view of a cleaning wafer with roundedprotrusions;

FIG. 4 is a perspective view of an embodiment of a chuck cleaning waferhaving multiple preformed radial ridges extending outwardly from thesurface of the cleaning wafer;

FIG. 5 is a perspective view of an embodiment of a chuck cleaning waferhaving differing protruding circular ridges;

FIG. 6 is a perspective view of underside of a chuck cleaning waferembodiment have a protruding edge ring;

FIG. 7 is a perspective view of an exemplary flat cleaning wafer withdiffering circular tack areas;

FIG. 8 is a perspective view of a wafer handling arm retrieving thecleaning wafer from a wafer tray;

FIG. 9 is a plan view of a bronze end effector with a vacuum cavity andport;

FIG. 10 is a plan view of a stainless steel end effector with a vacuumcavity and port;

FIG. 11 is a plan view of a bronze dipole arm end effector with multiplevacuum cavities and ports;

FIG. 12 is a plan view of a stainless steel rotational chuck for waferalignment;

FIG. 13 is a plan view of a Teflon rotational chuck for wafer alignment;

FIG. 14 is a perspective view of an example electrostatic chuck havingconcentric vacuum rings;

FIG. 15 is a perspective view of a quartz pin chuck showing the pin/burlpattern;

FIG. 16 is a perspective view of debris to be removed from a waferhandling arm by the cleaning wafer;

FIG. 17 is a perspective view of a cleaning wafer being loaded onto awafer stage, contacting the surface, removing particulate matter, andreleasing from the stage;

FIG. 18 is a perspective view of a compliant cleaning polymer conformingaround the burls and micro-burls on a pin chuck stage;

FIG. 19 is a series of photographs showing a pin array on a pin chucksurface, a higher magnification of debris on the pins, a highermagnification of the pins after cleaning with the chuck cleaning wafer,and a higher magnification of debris captured on the cleaning polymersurface;

FIG. 20 is a side view of the surface features compressing and allowingcontact between the cleaning polymer and a flat wafer stage.

FIG. 21 is a flow chart showing example process steps for use of acleaning wafer in an automated integrated chip wafer manufacturing tool;

Throughout the drawings, identical reference characters and descriptionsindicate similar, but not necessarily identical, elements. While theexemplary embodiments described herein are susceptible to variousmodifications and alternative forms, specific embodiments have beenshown by way of example in the drawings and will be described in detailherein. However, one of ordinary skill in the art will understand thatthe exemplary embodiments described herein are not intended to belimited to the particular forms disclosed.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

With reference to FIG. 2, a wafer substrate 10 is affixed to a cleaningpolymer sheet or cleaning surface 12 with the cleaning polymer sheet 12containing discrete protruding and other surface features 14 (shown asconical or pyramidal in FIG. 2). In some embodiments, these discreteprotruding surface features 14 are compressible. The wafer substrate 10is disc shaped and is made of silicon or any other material that allowsprocessing through wafer handling equipment. In certain embodiments, thegeometry is such that it is compatible with wafer handling equipment,such as, for example handling equipment sized 150 mm, 200 mm, 300 mm or450 mm in diameter and about 0.022 inches to 0.033 inches in thickness.In some embodiments, the cleaning polymer 12 is comprised of an elasticpolymer and may be an acrylic rubber, a urethane rubber, a butadienerubber, a styrene rubber, a nitrile rubber, or silicone rubber or anyother polymer that has a controlled surface tack, or surface adhesion,and does not transfer materials.

Referring now to FIG. 20, the elastic cleaning polymer 50 may be formedon the wafer base surface or substrate 48 to produce protruding surfacefeatures, e.g., 52, that provide offset or minimal contact with the flatsurfaces 54 of the wafer handling hardware 51 until a vacuum orelectrostatic force is applied. The application of predetermined forceto the cleaning wafer 49 can collapse the offset features e.g., 52,enabling the cleaning polymer 50 to come into contact with, and matinglyabut, the surface 54 of the wafer handling hardware 51. With the releaseof the compression force, the resiliency of the protruding andcompressible surface features, e.g., 52, urge them to resume theirformer shape, i.e., non-compressed form, to thereby separate the elasticcleaning polymer 50 from the surface 54 of the wafer handling hardware51. Due to the surface adhesion properties of the cleaning polymer 50,the undesirable debris adheres to the cleaning polymer 50 and is thusremoved from the flat surface 54 of the wafer handling hardware 51.

In some embodiments, wafer cleaning substrate material 50 is made ofsilicone, acrylic, polyurethane or any other elastic polymer that may beformed with a surface tack property between about 0.1 psi and 10 psi. Incertain embodiments, the elastic cleaning polymer material 50 isprocessed to be durable under repeated handling without a reduction insurface tack. In some embodiments, the material is sufficientlyprocessed and/or crosslinked such that transference from the cleaningsurface to the wafer handling hardware 51, wafer stage, and wafer chuckdoes not occur. It is to be understood, however, that materials otherthan polymers may be used to provide a substrate.

In some embodiments, control of surface tack and material transferenceof the elastic cleaning polymer 50 is achieved in the polymer phase bythe level of crosslinking density after processing. In a siliconeembodiment, the tack of the polymer surface can be controlled by theratio of platinum catalyst and multi-functional crosslinking resin tothe long chain gum polymer in the addition cure system. Some embodimentsmay also use a free radical curing system with the addition of peroxidecuring agents in a poly-dimethylsiloxane polymer system. Higher levelsof catalyst and crosslinking resin result in lower surface tack polymersin the addition cure system. Higher levels of peroxide curing agentresult in lower surface tack polymers in the free radical cure system.Low surface tack polymers will exhibit a Shore A durometer level above80, while high surface tack polymers will exhibit a Shore A durometerless than 35. An example of each system is Wacker Silicones Elastosil M4670 and Wacker Silicones Elastosil R401/70. Post processing to achievedesired surface tack levels and to remove free low molecular weightvolatile material that may contribute to transference is completed at200° C. to 300° C. under vacuum of 25 in. Hg for 60 minutes minimum. Insome embodiments, this process can serve to reduce or eliminate materialoff gassing according to gas chromatography testing at 150° C. for 60minutes. Low molecular weight volatile materials can be driven off asseen through gas chromatography testing and additional crosslinking canbe achieved during the post processing cycle as seen by an increase indurometer and material hardness testing.

In certain embodiments, filler materials may be added to the elasticcleaning polymer 50 to adjust the surface tack, change the color, orprovide a polishing action in addition to the tack for debriscollection. Control of surface tack and material hardness is achieved inthe polymer compound by the addition of particulate filler materials andas used in the fashion described herein. In that manner, the applicationof the cleaning wafer with these types of filler can accomplish abrasivecleaning through the typical contact between the elastic cleaningpolymer 50 containing the added abrasive filler materials and the waferhandling equipment surfaces. In at least one embodiment, the fillermaterial is aluminum oxide with an average particle size of 0.5 micronsat a loading of 70% of the total compound weight. The particle size canrange from 0.25 micron to 25 micron and the weight % loading can varyfrom 5% to 90% of the total compound weight. The filler particleselected should have a hardness number on the Mohs scale of 6 minimum.In some embodiments, the addition of filler particulate can affect ShoreA hardness of the compound from below 35 to above 80 as the loadinglevel increases.

In some embodiments, the electrostatic capability of the cleaning wafer49 is enhanced with an electrostatic filler, for example a metalliccomposition or compound interspersed within the cleaning polymer 50material in a fashion well known in the art. This electrostatic fillercan then be urged as desired into contact with the associated structurein the wafer manufacturing and wafer handling equipment that useelectrostatic force systems.

In reference now to FIG. 18, in at least one embodiment, the thicknessof the cleaning polymer sheet 38 is preferably about 0.001 inches to0.010 inches. In some embodiments, the thickness of the cleaning polymersheet 38 is sufficient to allow the material to deform around the burls,e.g., 44, and micro-burls, and collect debris, e.g., 42, that hasaccumulated around the periphery of the pin, e.g., 40, contact surface.Typically polymer compounds that exhibit high surface tack levels, suchas above 3.0 psi, that deform more readily with a durometer level belowShore A 50, will be used for wafer chuck pin arrays that have large pinsand larger pitch between pins. Typically polymer compounds that exhibitlow surface tack levels, such as below 3.0 psi, that are less compliant,such as durometer above 50, will be used for wafer chuck pin arrays thathave small pins and small pitch between pins and therefore high pincount per surface area.

Referring again to FIG. 2, in certain embodiments, the discreteprotruding surface features, e.g., 14, may be formed up to about 0.080inches high and may be oriented on the wafer substrate 10 to (i) contactor avoid certain areas of wafer handling hardware (not shown in FIG. 2)and the flat stage (not shown in FIG. 2) such as vacuum ports, etc, or(ii) to avoid the burls on a pin chuck surface (not shown in FIG. 2). Inat least one embodiment, the protruding discrete surface features, e.g.,14, are 0.020 inches high and are compression molded into or onto thesurface of the cleaning material. The molding is performed with acompression plate (not shown in FIG. 2) with a cavity (not shown in FIG.2) having the shape of the desired feature pattern and geometry. Thecompression plate press is typically held at 150° C. for 30 minutesunder 1 to 5 pounds per square inch pressure to form the features.

In some embodiments, an adhesive layer such as silicone or acrylicpressure sensitive adhesive (not shown in FIG. 2) bonds the cleaningpolymer sheet 12 to the bare silicon wafer used as wafer substrate 10.In some embodiments, the cleaning polymer sheet 12 extends across thewafer or wafer-like substrate surface 10 for complete coverage withoutany exclusion area. In certain embodiments, as needed, an edge exclusion(not shown in FIG. 2) to expose the wafer bead or protrusion, e.g., 14,may be incorporated. An edge exclusion can be created by laser removalof the outer one to two millimeters of the cleaning polymer sheet 12.

With reference to FIG. 5, a wafer substrate 10 is affixed to thecleaning polymer sheet 12 with the cleaning polymer sheet containingring-shaped protrusion surface features, e.g., 16. The ring-shapedprotruding features, e.g., 16, may be formed up to about 0.080 incheshigh from the wafer's base surface and may be oriented on the wafersubstrate 10 to contact features on the wafer handling hardware in orderto prevent or diminish contact of the cleaning polymer sheet withcertain areas of wafer handling hardware and flat stage areas, such as,for example, vacuum ports, or burls on a pin chuck surface (not shown inFIG. 5).

Referring now to FIG. 7, a wafer substrate 10 is affixed to the cleaningpolymer sheet 12 with a distinct area of different surface tack 18. Thethickness of the distinct area of different surface tack 18 issubstantially the same as the cleaning polymer area 12. The tack levelof the distinct area of different surface tack or variant tack area 18is sufficient to allow the material to release from certain waferhandling equipment such as a vacuum ring (not shown in FIG. 7). Thevariant tack area 18 may be oriented on the wafer substrate 10 invarious geometries to contact or avoid certain areas of wafer handlinghardware (not shown here) such as, for example, vacuum ports or rings(id.).

For example, with reference now to FIG. 20, in some embodiments acleaning wafer 49 comprising wafer substrate 48, polymer cleaningsurface 50, and compressible offset surface features, e.g., 52, may alsohave: (i) sections of no surface tack, e.g., 53, on the cleaning wafersurface 50 that may come into contact with sensitive features on theopposing surface 54 of the wafer handling equipment 51 (such as vacuumports or rings (not shown in FIG. 20)); as well as (ii) areas ofpositive tack, e.g., 55, on the polymer cleaning surface 50.

Returning now to FIG. 7, the variant tack area 18 of the cleaning waferpolymer surface 12 is produced by the placement of a rigid, tack freeplastic film 13 that has similar thickness to the adjacent cleaningpolymer layer 18. The rigid, tack free film 13 is bonded to the siliconwafer with an adhesive layer (not shown in FIG. 7) between the film 13and the cleaning polymer layer 18. In some embodiments the adhesive is asilicone or acrylic pressure sensitive adhesive. Also, in someembodiments the rigid, tack free film is comprised of polyethyleneterephthalate (PET).

In some embodiments the adhesive layer (not shown in FIG. 7) iscomprised of silicone or acrylic pressure sensitive adhesive. Thethickness of the adhesive layer (not shown) can range from 0.0001 inchesto 0.010 inches with the thickness in some embodiments being 0.003inches. The adhesive will have an adhesion level of 1.5 to 2.5 poundsforce per linear inch wide according to the PSTC101 test method. In someembodiments, the adhesive is pressure sensitive; however, the adhesivemay be a non-tacky bonding adhesive such as a heat seal, sealant orthermoset adhesive comprised of silicone, acrylic, polyurethane,cyanoacrylate or any other suitable material.

The cleaning polymer sheet 12 extends across the wafer or wafer-likesubstrate surface 10 for complete coverage without any exclusion area.If desired, the cleaning wafer substrate may have an edge exclusion orlip section (not shown in FIG. 7), to expose the wafer bead (not shownin FIG. 7).

With reference to FIG. 8, in some embodiments, one or more chuckcleaning wafers, e.g., 22, may be processed, loaded into, and unloadedby, a wafer handling arm 20, from a wafer carrier or wafer tray 24capable of containing one or more cleaning wafers, e.g., 22. The waferhandling arm 20 is part of the wafer processing tool (not shown in FIG.8). This wafer processing tool may be a photolithography tool such as astepper or scanner. The tool may also be a chemical vapor depositiontool (CVD) or a plasma vapor deposition tool (PVD). These types of toolsare supplied by companies such as Applied Materials, ASML, Canon, Nikon,etc.

Continuing with reference to FIG. 8, the end effector 21 (also e.g.,with reference to FIG. 9, 60, with reference to FIG. 10, 70, withreference to FIG. 11, 80, with reference to FIG. 12, 90, and withreference to FIG. 13, 100) of the wafer handling arm 20 is typically thedevice at the end of the wafer moving arm 20 that contacts the cleaningwafer 22 and secures it, in some embodiments, with a vacuum force as thewafer 22 is typically lifted and moved by the wafer handling arm 20. Insome embodiments, the wafer handling tool (not shown in FIG. 8) has avacuum gauge (not shown in FIG. 8) that measures the strength of thevacuum seal between the cleaning wafer 22 and the wafer handling arm's20 end effector 21. If the vacuum seal is not sufficient to hold thecleaning wafer 22 securely on the wafer handling arm 24, the chuckcleaning wafer 22 is not moved.

In some embodiments, upon being transported through the wafer handlingequipment by the wafer handling arm 24, the cleaning wafer 22 ispositioned over the surface of the wafer handling stage (not shown inFIG. 8) to be cleaned and placed upon the wafer handling stage'sretractable ejector pins (not shown in FIG. 8). In some embodiments, theejector pins, mounted in the wafer stage, also use a vacuum force tohold and position the chuck cleaning water 22 in place. The waferhandling equipment then handles the cleaning wafer 22 as it would a chipwafer. That is, the wafer stage's ejector pins retract, placing thecleaning wafer 22 on the surface of the wafer handling equipment to becleaned; the cleaning wafer 22 is impelled into contact with the waferhandling equipment, impelled, for example, by vacuum, electrostatic, ormechanical forces; the cleaning wafer 22 is then released by the forcesimpelling it into contact with the wafer handling component surface (notshown in FIG. 8); the wafer stage's ejector pins extend and convey thecleaning wafer 22 back into a position where the end effector 21 ofwafer handling arm 24 re-attaches to the cleaning wafer 22; and thewafer handling arm 24 removes the cleaning wafer 22 from the waferhandling component and returns it, in some embodiments, to a wafercarrier or wafer tray 24.

In some embodiments, the cleaning wafer or cleaning wafers 22 areautomatically removed from the wafer carrier or wafer tray 24 by thewafer handling arm 20 and cycled through processes of the tool undernormal conditions. The cleaning wafer 22 is cycled with the cleaningmedia typically facing down throughout the handling process so that thecleaning polymer sheet 12 (not shown in FIG. 8) may contact the flatsurfaces of the handling arm 20 thereby removing loose foreignparticulate matter from the handling arm surface. Handling of thecleaning wafer 22 by the handling arm 20 is facilitated by the cleaningpolymer surface 12 features shown in FIG. 2 as discrete surface features14, also shown in FIG. 5 as ring-shaped surface features 16, which keepthe cleaning surface 12 offset from the surfaces of the handlingequipment. FIG. 7 illustrates example variant tack areas 18 that allowprocessing of the cleaning wafer 22 by facilitating release from waferhandling arm 20.

Since chuck cleaning wafers 22 typically exhibit surface tack propertiesto clean the wafer chuck (not shown in FIG. 8), the tacky cleaningsurface (12 as showing in FIG. 7) of the cleaning wafer 22 tends toadhere to the flat surfaces of an end effector 21 interfering with therelease of the cleaning wafer 22 at the next station. The discretesurface features (14 as shown in FIG. 2) of the cleaning wafer 22 arepredetermined to reduce or minimize surface contact between the cleaningwafer 22 and the end effector 21 and allow the cleaning wafer 22 torelease from the end effector 21 and other components of the waferhandling mechanism, for example the wafer handling arm 20 while stillretaining the surface tack required for proper removal of debris fromthe wafer chuck (not shown in FIG. 8). In some embodiments, the surfacefeatures of the cleaning wafer 22 can be designed to reduce or minimizecontact with the flat surfaces of the end effector 21 and rotationalrings (not shown in FIG. 8) while still allowing the vacuum seal tooccur. Without a proper vacuum seal, some embodiments of the waferhandling tool (not shown in FIG. 8) will report a vacuum error andreturn the cleaning wafer 22 to the original loading tray 24 withoutprocessing it 22 as desired to effect cleaning. When all vacuums arepulled, full contact does place usually—at least enough to clean thetool and provide recoil.

In some embodiments, end effectors (e.g., those referenced in FIG. 9through FIG. 13) are somewhat interchangeable and their design typicallyvaries from tool to differing tool. The predetermined design of thediscrete feature pattern on the chuck cleaning wafer 22 is based on thegeometry and operation of the end effector 21 and, for example,rotational rings (not shown in FIG. 8). Thus, in some embodiments thecleaning wafer 22 can be customized to conform to the particulargeometry and operation of the particular wafer handling tool componentto be cleaned by the cleaning wafer.

With reference to FIG. 9, in some embodiments, a bronze end effector 60has a vacuum port 64 connected to, and evacuated through, vacuum tube 66in order to secure the cleaning wafer (not shown in FIG. 9 but see FIG.8, 22) during transport. The cleaning wafer will typically contact theend effector 60 on the flat surface areas 68.

With reference to FIG. 10, in another embodiment, a stainless steel endeffector 70 has a tip 72 contacting the center of the cleaning wafer(not shown in FIG. 12), a vacuum port 74 connected to a vacuum tube 76,and flat areas 78 to be contacted by the cleaning wafer. While thegeometry of each end effector, e.g. 70, determines the placement ofcleaning wafer surface features to facilitate cleaning and release ofthe cleaning wafer, the material composition of the end effector, e.g.,70, can affect adhesion of the tacky surface cleaning material of thecleaning wafer. The adhesion level of specific metal, plastic, orceramic components of the end effector, e.g., 70, rotational chuck (notshown in FIG. 12) and main chuck (not shown in FIG. 12) can be accountedfor during design of the cleaning wafer.

With reference to FIG. 11, in another embodiment, an end effector 80,has a tip 82 that serves to contact the center of the cleaning wafer(not shown in FIG. 13). This end effector 80 has five vacuum ports 84that can secure the cleaning wafer during transport and cleaning of theend effector 80 if desired.

With reference to FIG. 12, in another embodiment, a stainless steelrotational end effector 90 has a rotational arm that rotates and alignsthe cleaning wafer during processing within the chip manufacturingapparatus (not shown in FIG. 14). The rotational end effector 90contains two contact rings 92 with vacuum ports 94 to secure thecleaning wafer (not shown in FIG. 12) during operation. The rotationalend effector 90 contacts the center of the cleaning wafer and vacuumsecures the cleaning wafer in position on the effector 90.

With reference now to FIG. 13, another embodiment of apolytetrafluoroethylene or Teflon rotational arm end effector 100 issimilar in geometry to the stainless steel rotational end effector 90 ofFIG. 12. This rotational arm end effector 100 contains two vacuum ports104 in its rotating disk 102.

From these examples, it is evident that the geometry and surface featurepattern of each chuck cleaning wafer can be custom designed for surfacegeometry and material composition of each differing type of end effectorand each wafer handling tool.

With reference to FIG. 14, one embodiment of a flat electrostatic chuck110 has concentric vacuum rings 112 containing vacuum ports (not shownin FIG. 14), ejector pin holes 114, and a flat wafer contact surface116. A cleaning wafer (not shown in FIG. 14) is held in place on thechuck 110 by electrostatic force and upon removal of that force, thecleaning wafer's compressible offset surface features (see FIG. 2, 14,and FIG. 20, 52) facilitate release through stored elastic force fromcompression. These compressible offset surface features are arranged toavoid contact with the vacuum rings 112 in this case. It is evident thatthe cleaning wafer cleaning surface features (not shown in FIG. 14) mustbe custom designed for each wafer handling tool, accounting for the endeffector, rotational chuck, and main pin or electrostatic chuck, e.g.,110, while also accounting for the geometry and material compositions ofeach of these components.

With reference to FIG. 15, an embodiment of a pin chuck 120 with thematerial composition being quartz and contains protruding pins or burls,e.g., 122, on the surface that contact the cleaning wafer (not shown inFIG. 15) along with vacuum ports, e.g., 124, bolt holes, e.g., 126, andejector pins 128. The tacky surface of the cleaning wafer contacts thepins and burls, e.g., 122, and is held in contact by vacuum. Uponrelease of the vacuum, the debris on the pins is bonded to the cleaningwafer surface and removed with the cleaning wafer. As in manyembodiments, the protruding surface features on the cleaning wafer arearranged to avoid contact with the pins and burls, e.g., 122, thusallowing flat portions of the cleaning wafer surface to contact andclean the pin array with contact being effected by the vacuum orelectrostatic force that impels the cleaning wafer to the pin chuck 120.

With reference to FIG. 16, in at least one embodiment, the cleaningwafer 22 is positioned with its cleaning polymer side (not shown in FIG.16) facing the flat surface 24 of the wafer handling arm 20. When thereis foreign particulate matter 25 on the flat surface 24 of the handlingarm 20 and the cleaning wafer 22 is picked up by the wafer handling arm20 for transport to a process stage, during transport the cleaning wafer22 contacts the surface of the handling arm 20, and the foreignparticulate matter 25 then adheres to the cleaning polymer surface 22.Upon release of the cleaning wafer 22 from the handling arm 20 for thenext process stage, the foreign particulate matter 25 is collected onthe cleaning wafer surface 22 and carried away from the handling arm 20.

With reference to FIG. 17, in some embodiments, the cleaning wafer 28with a cleaning polymer side 30 is positioned onto a wafer stage 26.Upon application of a force such as a vacuum at approximately 16 to 24in. Hg, the cleaning surface 30 of the cleaning wafer 28 makes contactwith the surface of the wafer stage 26. If there is foreign particulatematter, e.g., 32, present on the surface of the wafer stage 26, then,upon release of the force holding the cleaning wafer 28 to the waferstage 26, the foreign particulate matter 32 adheres to the cleaningsurface 30 of the cleaning wafer 28 and is thereby removed from thewafer stage 26.

In further detail, still referring to FIG. 17, the cleaning polymer side30 of the cleaning wafer 30 has protruding compressible offset features(see FIG. 2, 14, and in FIG. 20, 52) designed to inhibit contact betweenthe cleaning wafer 28 cleaning surface and the surfaces of the waferstage 26 until a vacuum or electrostatic force is applied. Once theforce collapses the compressible offset features on the cleaning polymerside 30 of the cleaning wafer 30, the tacky polymer surface or cleaningpolymer side 30 contacts the surface of the wafer stage 26 to removeforeign particulates, e.g., 32. In the case of pin or burl chucks thecompressible offset features are positioned at locations outside the pinarea or in specific locations within the pitch of the pins and burls(see FIG. 18, 44, 46) so that the tacky cleaning surface of the cleaningpolymer 30 may make contact with the pin tips to remove debris. Thesmooth polymer 30 is sufficiently compliant to deform around the burlsand micro-burls (see FIG. 18, 44, 46) and collect debris that hasaccumulated around the periphery of the pin contact surface. In the caseof a chuck with vacuum ports, grooves, or vacuum nipples (not shown inFIG. 17), the locations of the compressible offset features of thecleaning wafer 28 polymer surface 30 are placed to facilitate debriscollection from within the vacuum features.

With reference to FIG. 18, in some embodiments a cleaning wafer (notshown in FIG. 20) is constructed with a compliant cleaning polymer 38that is capable of conforming around pins, e.g., 40, on a wafer pinstage 41. The compliant cleaning polymer 38 contacts the foreignparticulate matter, e.g., 42, on the wafer stage pins, e.g., 40, forcollection and removal from the wafer stage pins 40. The compliantpolymer 38 may also conform around micro-burls, e.g., 44, on a waferstage pins, e.g., 40 to contact the foreign particulate matter, e.g.,46, for collection and removal from the wafer stage 41.

In certain embodiments, with reference now to FIG. 18, the compliantcleaning wafer's cleaning polymer 38 conforms around the pins 40 on thewafer pin stage upon application of a vacuum force. In some embodiments,the polymer 38 is sufficiently compliant to deform around the burls orpins 40 and micro-burls, e.g., 44, and collect debris e.g., 42, 46 thathas accumulated around the periphery of a pin contact surface, e.g., 44.The protruding compressible offset surface features (not shown in FIG.18) the cleaning wafer (not shown in FIG. 18) placed outside of thepins, e.g., 40, allows the relatively smooth area of the cleaning waferpolymer 38 to contact the pin surfaces, e.g. 40. The protrudingcompressible offset surface features (not shown in FIG. 18) may beplaced to match locations of vacuum ports, grooves, or vacuum nipples(not shown in FIG. 18) to facilitate debris collection from within thevacuum features (not shown in FIG. 18).

With reference to FIG. 19, in at least one embodiment, wafer handlingequipment to be cleaned contains a quartz pin chuck, upon the surface ofwhich are an array of pins, e.g., section 8.A.1. During thephotolithographic manufacturing process and prior to cleaning with thecleaning wafer (not shown in FIG. 19), debris accumulates around thepins on the pin chuck surface, e.g., visible in the higher magnificationof section 8.A.2. The debris is typically transported in and left on thechuck pins by the silicon process wafers (not shown in FIG. 19).Immediately after contact with the cleaning wafer polymer e.g., section8.A.4, the loose debris has been removed from the pin tip andcircumference, e.g., section 8.A.3 and now the residual debris that wasremoved from the pins resides on the surface of the cleaning polymer,e.g., section 8.A.4. In this and other embodiments, the cleaningpolymer, e.g., section 8.A.4, does contact the pins and is compliantenough to conform around the pin tip and somewhat down the side, and thecleaning polymer is sufficiently tacky to bond to and remove loosedebris from the chuck pins.

Referring now to FIG. 20, in some embodiments, a cleaning wafer 49, witha cleaning polymer surface 50 on a wafer-like substrate 48 hasprotruding and compressible surface features, e.g., 52, on the cleaningpolymer 50 that provide offset and limit contact between the cleaningpolymer surface 50 and a wafer stage surface 54. The elastic polymerformed on the cleaning wafer surface 50 to produce protruding andcompressible features, e.g., 52, provides offset or minimal contact withthe flat surfaces of the wafer stage 54 until a vacuum or electrostaticforce is applied. Once the vacuum force collapses the compressibleoffset features, e.g., 52, the tacky polymer surface 50 contacts thesurface 54 of the wafer stage 51 to remove foreign particulates, e.g.,56. Upon release of the compression force, the offset features, e.g., 52rebound and facilitate release from the wafer stage 51 while the foreignparticulate matter 56 adheres to the cleaning polymer 50 and is removedfrom the wafer stage 51.

The polymeric cleaning material 50, should have a measurable surfacetack between 0.01 and 10 psi using standard ASTM based methods forcollection of foreign particulate and to allow release of the cleaningmaterial 50 from the stage surface 54 depending on stage geometry. Thesurface features, e.g., 52, are also dependent on the chuck or stagegeometry. In some embodiments, features that collapse on a wafer stage,such as wafer stage 54, to allow contact for debris collection mayusually do so at less than 6 psi vacuum force. The surface tack of thecleaning material 50 is typically low enough that the cleaning wafer 49releases from the wafer stage 51 at less than 4.5 psi pressure on eachejector pin (normally at about 3.0 psi pressure). In at least one methodof use, the vacuum is held for a minimal period such as 5 to 15 seconds,which allows full contact of cleaning surface 50 on the wafer stage 51to collect debris but facilitates release.

A cleaning wafer can be loaded and cycled automatically in most toolsbut may also be loaded manually in tools with access to the main chucksuch as an ASML PAS5500 stepper. The cleaning wafer can also be manuallyloaded into a plasma vapor deposition tool such as Applied MaterialsEndura HP by processing in the first pre-clean chamber to control debrisaccumulation. While reducing cycle time of the vacuum on a pin chuckfacilitates release of the cleaning polymer while retaining cleaningeffectiveness the same can be accomplished on an electrostatic chuck byreducing cycle time to 5 to 15 seconds and reducing the applied voltageto 150V or less.

Referring now to the flowchart of FIG. 21 in conjunction with thediagrams of FIG. 2 and FIG. 8, in one embodiment of a method ofimplementation, the cleaning wafer 10 is securely wrapped to protect itfrom contamination during shipment and pre-cleaning handling. At step200, upon first usage of the cleaning wafer, the protective surfaceliner is removed and discarded. At step 202, wafer substrate 10 may bemanually loaded or loaded in an automated manner. At steps 204 and 206,a single cleaning wafer 22 or multiple wafers 22 may be placed cleaningmaterial side down (or wafer side up) in a wafer carrier 24, wafer tray,or other wafer loading device of the desired wafer processing tool. Atstep 202, the cleaning wafer 22 or cleaning wafers 22 are automaticallyremoved from the wafer carrier 24 or wafer tray and cycled throughprocesses of the tool under normal conditions. The cleaning wafer may becycled with the cleaning surface 12 facing down throughout the handlingprocess. Within the tool, standard handling is facilitated by thewafer's protruding surface features, e.g., 14, which keep the cleaningsurface 12 offset from the surfaces of the handling equipment. At step208, wafer carrier 24 may be installed to a load port of the automatedwafer processing tool.

At step 210, the wafer substrate 10 may be moved with, for example,handling hardware, end effector, or a wafer handling robot arm 20 andthen unloaded.

At step 212, debris 25 is removed via vacuum of the flat contact area ofthe handling hardware. At step 214, the wafer 10 is placed on waferstage 26, wafer chuck apply vacuum or electrostatic charge. At step 216,the wafer may be released from the wafer state 26 or wafer chuck.Similar to step 212, at step 218 debris 25 may be removed via vacuum ofthe flat contact area of the handling hardware. At step 220, wafersubstrate 10 may be manually loaded or loaded in an automated manner.

At step 222, the wafer 10 is returned to wafer carrier 24 installed atthe load port of the processing tool. Alternatively, at step 224 thewafer 10 is returned to a single wafer tray. At step 226, the wafersurface is inspected.

Thus, in some embodiments shown by way of example in FIG. 21, thecleaning media 12 is placed on the surface of each wafer chuck or waferstage 26 within the automated wafer processing tool, makes near full orfull surface contact through vacuum assist on a flat stage or by restingon the burls in a pin chuck for a specific dwell time, collects foreignparticulate matter 25, and is then cycled back to the wafer carrier tray24 and subsequently unloaded.

In some embodiments, the method of creating a cleaning wafer begins withthe wafer handling equipment manufacturer providing details on the waferhandling components and chuck geometry of the specific equipment forwhich the cleaning wafer is intended. Based upon the manufacturerspecifications, several potential designs are prepared and prototypecleaning wafers produced. These prototype cleaning wafers have a lowlevel of tack, for example, a level 3 on a scale from 1 to 10 fordesired range of tack for a given application or tool. These prototypecleaning wafers are run through the actual machine, with each design andgeometric configuration being tested for consistency of successfulthroughput and quantity of foreign particulate accumulated.

Based upon the results of the initial tests, the designs are modifiedand new prototype cleaning wafers are produced. These new, revisedprototype cleaning wafers are then tested with increasingly higherlevels of tack, determining for each design, what is the highest levelof tack it can include and yet still function with acceptableconsistency. The cleaning wafer that performs the best in the tests isthen designated to be the cleaning wafer for that particular waferhandling equipment.

In other embodiments, a cleaning wafer may be comprised of two polymercleaning surfaces, positioned on opposite faces of the cleaning wafer.In some embodiments, a two-sided cleaning wafer is designed for use inwafer bonding equipment. Wafer bonders join two or more alignedsubstrates to create an integrated circuit. The substrates can bejoined, or bonded, using the following techniques: fusion bonding,anodic bonding, eutectic bonding, solder bonding, glass frit bonding,adhesive bonding. Temporary wafer bonding is performed on thinned wafersplaced on a carrier for support. This process is used mainly tomanufacture 3D integrated circuits. SUSS MicroTec produces equipmentthat supports these bonding techniques. A two-sided cleaning wafer maybe manufactured using the techniques described above, but for each sideof the wafer. This can yield a cleaning wafer having predeterminedsurface features on both sides to clean components of bonding equipmentby cycling the wafer through the equipment. Two sided cleaning wafersmay also be utilized to clean wafer handling equipment in othercircumstances, such as when having two cleaning surfaces is advantageousto clean two or more components, at least one with one side of thecleaning wafer and another with the other side. The cleaning wafer couldalso similarly include other sides having such predetermined features toclean yet other components in wafer handling equipment.

In other embodiments, a cleaning wafer may be designed to remove debrisfrom areas of photolithography tools, such as reticles, mask frames,mask loading equipment, and the mask surfaces. Reticles or masks containthe image of the particular circuit pattern that is projected onto thewafer surface in a stepper or scanner for example. In a manner similarto that described in the wafer process through the tool, debris canaccumulate along the mask area on the handling equipment used to loadand unload the mask, the frame that holds the mask, and on the masksurface. Similar cleaning material with the same product attributesincluding surface features may also be used to remove debris from thisarea of the tool. The material in this case may be mounted to asurrogate mask such as a quartz block to transport the cleaning materialthough the tool and allow it to contact the handling surfaces to removeaccumulated debris. It will also allow contact with the frame that holdsthe mask here if debris is present it may not allow the mask to seatproperly and cause focus issues. The cleaning material may also contactthe mask surface offline to remove debris before installing the mask inthe photolithography process. This procedure can provide non-destructivecleaning, particularly as compared the techniques that apply solvents ormanual scrubbing or abrasion that reduce the lifetime of the mask.

It can thus be seen that the embodiments described above may providemany advantages. They can include in some embodiments:

more efficient wafer stage cleaning with less or even no tool downtime;

improved and more effective wafer handling cleaning;

more economical wafer handling equipment cleaning;

more productive wafer handling equipment cleaning; and

less corruption of the wafer handling hardware, wafer stage, and waferchuck during the cleaning process.

While the foregoing written description enables one of ordinary skill tomake and use what is considered presently to be the applicants' best andother modes, those of ordinary skill will understand and appreciate theexistence of variations, combinations, and equivalents of the specificembodiments, methods, and examples set forth in this specification.

1. A semiconductor manufacturing apparatus cleaning system comprising: asemiconductor manufacturing apparatus having first and second surfacessubject to contamination during operation of the apparatus; a cleaningwafer comprising a resilient cleaning pad having a cleaning side with atacky area and a compressible tack-free area protruding above the tackyarea; and an arm adapted to carry the cleaning wafer, the arm movable toposition the cleaning wafer adjacent the first surface, force the tackyarea against the first surface and thereby compress the tack-free area,and then release, whereby the tack-free area decompresses and urges thecleaning wafer away from the first surface.
 2. The system of claim 1wherein the arm is movable to position the cleaning wafer adjacent thesecond surface, force the tacky area against the second surface andthereby compress the tack-free area, and then release, whereby thetack-free area decompresses and urges the cleaning wafer away from thesecond surface.
 3. The system of claim 1 wherein the tacky area isshaped to conform to the first surface.
 4. The system of claim 1 whereinthe tacky area comprises two sub-areas of differing thicknesses.
 5. Thesystem of claim 4 wherein at least one of the sub-areas is shaped toconform to the first surface.
 6. The system of claim 4 wherein the armis movable to orient the cleaning wafer to align at least one of thesub-areas with the first surface.
 7. The system of claim 1 wherein thetacky area comprises two sub-areas of differing levels of tack.
 8. Thesystem of claim 7 wherein at least one of the sub-areas is shaped toconform to the first surface.
 9. The system of claim 7 wherein the armis movable to orient the cleaning wafer to align at least one of thesub-areas with the first surface.
 10. The system of claim 1 wherein thefirst surface is grooved, whereby air can pass through the groovebetween the first surface and the cleaning wafer while the wafer isbeing forced against the first surface.
 11. The system of claim 1wherein the tacky area is compliant to deform around the first surface.12. The system of claim 11 wherein the arm is movable to orient thecleaning wafer to align with the first surface.
 13. The system of claim11 wherein the tacky area comprises at least two sub-areas of differingcompliance properties.
 14. The system of claim 13 wherein a first one ofthe sub-areas is shaped to conform to the first surface.
 15. The systemof claim 13 wherein the arm is movable to orient the cleaning wafer toalign the first one of the sub-areas with the first surface.
 16. Thesystem of claim 13 wherein a first one of the sub-areas is shaped toconform to a first portion of the first surface and a second one of thesub-areas is shaped to conform to a second portion of the first surface.17. The system of claim 13 wherein the arm is movable to orient thecleaning wafer to align the first one of the sub-areas with the firstportion of the first surface and the second one of the sub-areas withthe second portion of the first surface.
 18. The system of claim 2wherein the tacky area comprises at least two sub-areas of differingcompliance properties.
 19. The system of claim 18 wherein a first one ofthe sub-areas is shaped to conform to the first surface and a second oneof the sub-areas is shaped to conform to the second surface.
 20. Thesystem of claim 19 wherein the arm is movable to orient the cleaningwafer to align the first one of the sub-areas with the first surface andthe second one of the sub-areas with the second surface.
 21. Asemiconductor manufacturing apparatus cleaning system comprising:cleaning means including means for adhering to contaminants on a firstsurface of the apparatus and means for urging the cleaning means awayfrom the first surface; and means for urging the cleaning means againstthe first surface, whereby contaminants adhere to the cleaning meanswhen the cleaning means is urged against the first surface and areremoved from the first surface when the cleaning means is urged awayfrom the first surface.
 22. The system of claim 21 wherein the means foradhering is shaped to conform to the first surface.
 23. The system ofclaim 21 wherein the means for adhering comprises two sub-areas ofdiffering tackiness.
 24. The system of claim 21 wherein the means foradhering is compliant to deform around the first surface.
 25. The systemof claim 21 wherein the means for adhering comprises at least twosub-areas of differing compliance properties.
 26. The system of claim 25wherein a first one of the sub-areas is shaped to conform to the firstsurface and a second one of the sub-areas is shaped to conform to asecond surface of the apparatus.
 27. The system of claim 21 wherein thecleaning means has an integrated-circuit wafer shape and the means forurging the cleaning means away from the first surface comprises acompressible protrusion extending from a cleaning surface of thecleaning means.